96 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



filaments I have never seen fewer than 32 megazoospores 

 in a cell. 



The microzoospores, or zoogametes, are much smaller. 

 They are ovate biciliate, actively motile cells, very pale 

 green at the broader end, and colourless at the point of 

 attachment of the two long cilia. They are produced in 

 vegetative cells, and, so far as I could make out, in other 

 filaments than those which produce megazoospores. The 

 contained mass of zoogametes is much paler in colour than 

 is the content of a megasporangium. The number of 

 zoogametes is 64 or more. Their movements are so rapid 

 that it is almost impossible to count them as they escape, 

 the calculation " 64 or more" is based, therefore, on the 

 appearance of the gametangium previous to their escape. 

 I have no doubt that conjugation takes place between 

 cells of the same filament. The mode of conjugation does 

 not differ from that described for Ulothrix zonata, by 

 Dodel Port,* although the tailed megazoospore and the 

 number of these produced in a sporangium places this 

 species in the genus Urospora, Aresch. I have not been 

 able to trace the after history of the zygote. 



The extrusion of mega- or micro-zoospores from a cell 

 lying between two others whose contents have not been 

 shed is followed by the profusion of the special cell-wall of 

 one of the lateral cells into the cavity, the gametes, or 

 spores of the latter escaping by the rupture already formed 

 in the outer wall of the empty cell. (See PI. III.) 



Chcetomorpha tortuosa, Kiitz. 



Prince's Pier, I. of Man, Aiiglesea. 

 C. linum, Kiitz. 



Anglesea !, Puffin I. ! 

 C. melagonium, Kiitz. 



Puffin I. ! I. of Man. Marrat records this spe- 

 * Priiigsheim's Jahrb. f. wiss. Bot., Bd. X. 



